Guinan first meets Picard and the crew of the Enterprise in the 19th century, I don't recall the episode to well, but I believe they do let her know that time that they are from the future, including that they are friends in the future.

Was Leia raised with the knowledge she was adopted?

As for Pe dying, I always assumed that was Palpatine. In most cultures I am aware of magic is not "free", everything has a cost, and with how much of the mythology of The Force centres on balance the idea that to "save a life one needs to take a life" makes complete sense. So I just always assumed that Palpatine siphoned Pe's life force into Anakin to keep him alive.